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I have 3 sets of conductors entering a generator enclosure in pvc. from there they go into the breaker enclosure (no conduit) through chase nipples. do I need to cut slots in the enclosure base at the nipples to prevent heating. I know about grouping each set together(example) A,B,C,N through one chase nipple etc. I remember some time ago cutting perpendicular slots in the enclosure?
 

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Salty Member
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Or Isolated phase. :)


300.3(B)(1)

Exception: Conductors installed in nonmetallic raceways
run underground shall be permitted to be arranged as isolated
phase
installations. The raceways shall be installed in
close proximity, and the conductors shall comply with the
provisions of 300.20(B).
 

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Salty Member
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I should have mentioned that the code section 300.20(B) cited in the isolated phase exception is the section that can require slots be cut as the OP was asking about.


300.20(B) Individual Conductors. Where a single conductor
carrying alternating current passes through metal with magnetic
properties, the inductive effect shall be minimized by
(1) cutting slots in the metal between the individual holes
through which the individual conductors pass or (2) passing
all the conductors in the circuit through an insulating wall
sufficiently large for all of the conductors of the circuit.

Exception: In the case of circuits supplying vacuum or
electric-discharge lighting systems or signs or X-ray apparatus,
the currents carried by the conductors are so small that
the inductive heating effect can be ignored where these conductors
are placed in metal enclosures or pass through metal.
 
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